A mass whale stranding in Loza Lagoon off Madagascar on 2008 has been attributed to high-frequency mapping sonar systems, researchers said.

An investigatory team determined the stranding of 100 melon-headed whales was caused by an echo-sounder system operated by a survey vessel, Science Recorder reported Thursday.

When the stranding occurred, the Wildlife Conservation Society worked with an international stranding team to help return live whales to the ocean and conducted necropsies to help determine what led to such a large number of whales to become stranded.

The final report, issued Wednesday, said the incident was the first mass stranding attributed to high-frequency mapping sonar systems. The findings also said there were serious concerns about the noise created by sonar machines and their impact on marine life.

"The potential for behavioral responses and indirect injury or mortality from the use of similar MBES [multi-beam echo-sounder systems] should be considered in future environmental assessments, operational planning and regulatory decisions," the report said.